The invention relates to a method for operating a gas burner according to the preamble of claim 1.
Gas burners normally comprise an electric or electronic ignition means and a flame monitoring means which normally measures an ionization current induced by the burner flame and, dependent on this ionization current, indicates the presence or absence of the burner flame.
There also exist controllers for gas burners which use the ionization current for guaranteeing a high combustion quality. In order to ensure an optimum and complete combustion of the fuel, i.e. the gas, within the gas burner, the latter has to be provided with an appropriately balanced gas/air mixture. For instance, the prior art discloses control methods using an ionization signal of a sensor projecting into the burner flame for adapting the gas/air mixture to, e.g., different gas qualities thereby adapting the gas/air mixture to the quality of the gas provided by the gas supply and guaranteeing a high combustion quality in the end. With respect to this, it can be referred to the DE-A-44 33 425, DE 39 37 290 A1, as well as the DE 195 39 568 C1.
In the known methods for operating a gas burner in which an ionization signal is used, there does, however, arise the problem that with increasing operating duration, the ionization signal provided by a sensor becomes unreliable. Then, a reliable information on the combustion conditions actually prevailing in the burner is no longer possible.
Proceeding from this, the present invention is based on the problem of providing a new method for operating a gas burner.
In accordance with the invention, the problem is solved by a method comprising the features of claim 1.